The present invention relates to air flow measurement devices and in particular to such devices of the rotor type.
Instruments to measure the ability of a human's lungs to inhale and/or exhale are known as spirometers. Spirometers have heretofore been developed which utilize a rotor for air flow detection and measurement. Such devices are disclosed, for example, in U.S. Pat. Nos. 3,949,737 and 4,034,743 as well as British Pat. No. 1,302,375. The devices disclosed in these references utilize relatively complex mechanisms to convert rotation of the rotor into a measurement of air flow and, as a result, are complex and expensive. In addition, each of these devices fail to take into consideration the fact that the rotor will tend to continue spinning after the air flow cycle has been complete.
In view of the above, it is a principal object of the present invention to provide a relatively simple and inexpensive spirometer of the rotor type.
It is a further object to provide such a spirometer which displays information in a form which may readily be interpreted.
A still further object is to provide such a spirometer which can detect both inhalation and exhalation and which can operate at very low air flows (as when used by an elderly or ill person).
Still another object is to provide such a spirometer which can be used in virtually any environment and which is not effected by humidity in the air flow stream.
Still a further object is to provide such a spirometer which is lightweight, portable and readily and easily utilized with a minimum of training required for its operation.
Still other objects will be apparent from the following description of a preferred embodiment of the invention.